There are three economic systems in world at war: Central planning, Free market, and Mixed Economy. The economic system of a world will determine what policies are available to that world, and how it is affected by trade. Economic systems can be changed once per turn by Nationalizing/Privatising business, which results in a moderate stability drop.
Free Market economies are able to increase their growth by buying bonds at 100 GEU per attempt (details in Economic Policies).
(Far Right end of the economic system. Requires 2 Nationalizations to reach Central Planning)
Mixed economies are able to buy bonds and also use Quantitative Easing to provide growth at the cost of some stability. They are also able to invest up to 1200 GEU into Industrial Programs to gain a set amount of growth per turn (+1 growth per 80 GEU invested).
(Middle of the Economic spectrum. One Nationalization/Privatization will switch a world's economy to Free Market or Central Planning, respectively)
Central Planning economies are able to improve their productive models to increase growth by 2 at the cost of 100 GEU per attempt. They are also able to invest up to 2400 GEU into Industrial Programs to gain a set amount of growth per turn (+1 growth per 60 GEU invested).
(Far Left end of the economic system. Requires 2 Privatizations to reach Free Market)